This invention relates to saws designed primarily, but not exclusively, for cutting very hard materials such as glass, tile, stone and the like, and has particular reference to so-called xe2x80x9cring sawsxe2x80x9d having a cutting tool or element in the form of a ring with an open center and supported on a base for rotation about a central axis.
Saws of this general type typically use cutting rings that are coated with an abrasive such as diamond particles, and have a work surface for supporting a workpiece to be cut as it is moved relative to the rotating ring into engagement with a working section of the ring where it passes through an opening in the work surface. A prior ring saw of this general type is shown in U.S. Pat. No. 4,576,139, which discloses a saw blade comprising a single strand of high tensile strength wire that is round in cross-section and is formed into a closed circular loop and covered with an abrasive coating so as to be equally capable of cutting in all directions. The ring is made as rigid as is possible with a wire of small diameter, usually less than one-quarter to one-half inch, and preferably about one-eighth inch in the commercial embodiment. The ring is supported and guided by the saw assembly around all of its circumference except for a short working section adjacent to the work surface where the cutting occurs. A frictional drive wheel rotates the ring at high speed. This patented saw has been very popular for use in cutting intricate shapes in materials like stained glass, but has limited capability for heavy work like cutting relatively thick pieces of file or stone, primarily because of the limited strength of the wire, particularly in small diameters desirable for fine cutting.
In one sense, the present invention is an improvement over the wire ring saw shown in the above-identified patent, and, in another sense, is a departure from blade and support concepts disclosed in that patent, so as to overcome the limitations of the wire ring saw with respect to heavy-duty cutting of relatively thick materials such as tile and stone while maintaining the ability to cut curves in such materials, and at the same time enhancing the capabilities of the saw in other respects.
For the foregoing purposes, the saw apparatus of this invention utilizes a blade ring that is not wire, but rather is a narrow flat-sided ring having sufficient radial width to be self-sustaining in shape during the cutting operations, permitting more than half of the ring blade to be exposed above the work surface and supported and driven in a novel fashion, that may be entirely beneath the work surface. This produces a blade ring of generally rectangular cross-section, having narrow inner and outer peripheral edges and relatively wide sidewalls, which should be at least twice the thickness of the outer peripheral edge. Typically, the blade ring is covered with an abrasive coating on the outer peripheral edge and at least partially on its sidewalls, for side-cutting. It is supported between guides engaging one of the peripheral edges, preferably the inner edge, along a substantial arc that may be entirely beneath the work surface, and by a drive element engaging the other peripheral edge, preferably the outer, and serving as a support for the blade ring as well, the preferred drive element being an endless belt having one run trained around a substantial arc along the underside of the blade ring, opposite the guides. The preferred guides are rollers rotatably mounted on the base and angularly spaced apart along the inner edge of the blade ring.
As is customary, a reservoir of liquid such as water for cooling the ring during cutting preferably is incorporated in the apparatus beneath the base, herein positioned so that the drive belt picks up coolant from the reservoir and carries it to the blade ring. Further, an optional stabilizer is provided for the upper portion of the blade ring with guides positioned on opposite sides of the blade ring to maintain the blade ring in its proper plane of operation. This is in the form of an arm overlying and tangent to the blade ring, and including a wiper for catching excess coolant carried by the blade ring.
Other aspects and advantages of the invention, including detailed aspects of the guides and drive, will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, in which: